1. Field of the Invention
The present invention relates to a method for producing a novel pest control agent having a 2-acyliminopyridine structure.
2. Related Background Art
Although many pest control agents have been developed so far, novel agents are still sought because of problems associated with decreased drug sensitivity, persistence of the effects of agents, safety of agents in use, and the like.
In particular, as shown in Masaya Matsumura et al., Pest Management Science, 2008, Vol. 64, No. 11, pp. 1115 to 1121 (Non-Patent Document 1), wet rice cultivation in East Asia and Southeast Asia obviously suffers damage due to planthoppers which have developed drug resistance to major pesticides including neonicotinoids represented by imidacloprid, phenylpyrazole-based agents represented by fipronil, and the like. Accordingly, specific agents against planthoppers which have developed resistance have been expected. In addition, it is required that such novel agents be provided in amounts required as pest control agents stably and at low costs.
Methods described in DESCRIPTION of European Patent Application Publication No. 432600 (Patent Document 1), Japanese Unexamined Patent Application Publication No. Hei 05-78323 (Patent Document 2), DESCRIPTION of European Patent Application Publication No. 268915 (Patent Document 3), and Botho Kickhofen et al., Chemische Berichte, 1955, Vol. 88, pp. 1103 to 1108 (Non-Patent Document 2) are known as methods for producing a pest control agent having a 2-acyliminopyridine structure. Patent Document 1 discloses a herbicide having the same ring structure as that of a compound represented by formula (I) described later. Patent Documents 2 and 3 disclose pesticides having the same ring structure as that of the compound represented by formula (I). Non-Patent Document 2 discloses a compound having a ring structure similar to that of the compound represented by formula (I), as a synthetic intermediate.
However, the production methods described in Patent Documents 1, 2, and 3, and Non-Patent Document 2 are production methods in which a compound represented by formula (Ba) described later is used as an intermediate, and fail to describe production in which a compound represented by formula (B) described later is used as an intermediate. Moreover, Patent Documents 1, 2, and 3, and Non-Patent Document 2 disclose production methods in which a compound represented by formula (Ba) is used as an intermediate, but do not specifically describe the production of a compound represented by formula (Ia) described later. Further, the structural formula of N-[1-((6-chloropyridin-3-yl)methyl)pyridin-2(1H)-ylidene]-2,2,2-trifluoroacetamide is disclosed, and a physical property value of the compound, i.e., a refractive index nD (25.5) of 1.4818 is described (Compound No. 3 in Table 1 of Patent Document 2); however, this compound is not included in the list of compounds shown to have pest control activities (Tables 2 and 3 of Patent Document 2).
Moreover, Patent Document 3 discloses the structural formula of N-[1-((6-chloropyridin-3-yl)methyl)pyridin-2(1H)-ylidene]-2,2,2-trifluoroacetamide, and describes a physical property value of the compound, i.e., a melting point of 60 to 62° C. (Example No. 12 in Table 7 of Patent Document 3). However, this compound is not listed in the examples of compounds which exhibited pest control activities in Examples. Neither Patent Document 2 nor Patent Document 3 discloses a specific method for producing N-[1-((6-chloropyridin-3-yl)methyl)pyridin-2(1H)-ylidene]-2,2,2-trifluoroacetamide.
In addition, Wladysl, aw Pietrzycki, et al., Bulletin des Societes Chimiques Belges, 1993, Vol. 102, No. 11-12, pp. 709 to 717 (Non-Patent Document 3) discloses N-(pyridin-2(1H)-ylidene]-acetamide as a tautomer of 2-acetamide pyridine, but fails to describe a specific method for producing the tautomer, or a method for producing a haloacyl derivative thereof.